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Equipment Stop
A field-supplied single pole single throw switch can be used
to shut down the unit operation. This switch is a binary
input wired to the customer connection, wired to 1XD24
(see unit diagrams). Ensure the appropriate jumper wire at
1XD24 is removed when this switch is installed. When
opened, the unit shuts down immediately and can be
canceled by closing the switch. The switch must be rated
for 12 ma @ 24 VDC minimum.
Ventilation Override Mode (VOM)
Contacts
Ventilation Override Modes (VOM) give the building
controller the ability to override normal unit operation and
provide special ventilation operation. VOM is initiated only
at the provided five binary inputs (Mode A, Mode B, Mode
C, Mode D, Mode E). When any of the normally open
contacts are closed, VOM initiates specified functions such
as space pressurization, relief, purge, purge with supply air
pressure control, and unit off when any one of the
corresponding binary inputs are activated. The
compressors and condenser fans, and all other
components not directly controlled via VOM events, are
disabled during the ventilation operation. If more than one
ventilation sequence is activated, Mode A has highest
priority, Mode E has lowest.
This function gives the customer the ability to override
normal unit operation via a supervisory controller. Typically,
these requests originate from a fire control panel. Flexibility
is provided by allowing the customer to re-define each of
the five responses at the front panel, along with allowing
each individual response to be 'Locked' to insure expected
operation is not changed. See Programming Guide for
more information.
This feature is optional. When configured VOM has priority
over Emergency Override, System Mode Off, and normal
unit operation. The following overrides will prevent or
terminate VOM operation.
•
Local Stop
•
Equipment Stop
•
Emergency Stop
•
Manual Control
When any VOM Mode (A, B, C, D, E) input is activated or
closed, the VOM mode of operation will begin in less than
10 seconds, and a VOM Relay binary output will energize/
close. Heating capacity, cooling capacity, and Rapid
Restart will be disabled/terminated.
Refer to
Table 32, p. 59
summarizing the unit operation in
response to VOM binary inputs Modes. VOM inputs are
fully configurable; therefore,
factory default settings.
If one or more of the 5 VOM inputs are closed, the unit will
enter the VOM mode with the highest priority (A highest, E
lowest). Should the unit be in an active VOM mode and a
VOM input of higher priority is closed, the unit will
immediately transition to the higher priority mode. Should
RT-SVX072D-EN
Table 32, p. 59
provides the
the unit be in an active VOM mode and a VOM input of
lower priority is closed, the unit will not change to this lower
priority mode until the current (higher priority) VOM mode
binary input is opened.
When all VOM inputs are open, within 15 seconds, VOM
terminates. All unit components will be reset OFF or
CLOSED, and after Unit Power Up Delay is honored, the
unit will start normal operation.
These functions are controlled by binary inputs wired to the
VOM. They can be initiated by a toggle switch, or a time
clock. The switch must be rated for 12 ma @ 24 VDC
minimum.
Table 32. VOM
VOM Input
Output
Mode A
Supply fan
(Unit Off)
Outdoor air
damper
Relief fan /
Relief damper
Return Fan /
Relief Damper
VAV Box Relay
Mode B
Supply fan
(Pressurize)
Outdoor air
damper
Relief fan /
Relief damper
Return fan /
Relief damper
VAV Box Relay
Mode C
Supply fan
(Depressurize)
Outdoor air
damper
Relief fan /
Relief damper
Return fan /
Relief damper
VAV Box Relay
Mode D
Supply fan
(Purge)
Outdoor air
damper
Relief fan /
Relief damper
Return fan /
Relief damper
VAV Box Relay
Installation
Operation
Heat Cool
Mode Status
Off/0%
Off
Closed
Off/Closed
Off/Closed
Energized
(1)
On/100%
Fan Only
100%
Off/Closed
Off/Closed
Energized
Off/0%
Fan Only
0%
On/Open
On/Open
De-engerized
(1)
On/100%
Fan Only
Open
On/Open
On/Open
Energized
59
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